USS SC-21

USS SC-21, until July 1920 known as USS Submarine Chaser No. 21 or USS S.C. 21, was an SC-1-class submarine chaser built for the United States Navy during World War I.

History
United States
Name	USS Submarine Chaser No. 21 (1917-1920) USS SC-21 (1920-1921)
Builder	New York Navy Yard, Brooklyn, New York
Commissioned	20 September[1] or 19 October[2] 1917
Reclassified	SC-21 on 17 July 1920
Fate	Sold 24 June 1921
General characteristics
Class & type	SC-1-class submarine chaser
Displacement	77 tons normal 85 tons full load
Length	110 ft (34 m) overall 105 ft (32 m) between perpendiculars
Beam	14 ft 9 in (4.50 m)
Draft	5 ft 7 in (1.70 m) normal 6 ft 6 in (1.98 m) full load
Propulsion	Three 220 bhp (160 kW) Standard Motor Construction Company six-cylinder gasoline engines, three shafts, 2,400 US gallons (9,100 L) of gasoline; one Standard Motor Construction Company two-cylinder gasoline-powered auxiliary engine
Speed	18 knots (33 km/h)
Range	1,000 nautical miles (1,900 km) at 10 knots (19 km/h)
Complement	27 (2 officers, 25 enlisted men)
Sensors & processing systems	One Submarine Signal Company S.C. C Tube, M.B. Tube, or K Tube hydrophone
Armament	1 × 3-inch (76.2 mm)/23-caliber gun mount 2 × Colt .30 caliber (7.62 mm) machine guns 1 × Y-gun depth charge projector

SC-21 was a wooden-hulled 110-foot (34 m) submarine chaser built at the New York Navy Yard at Brooklyn, New York. She was commissioned on either 20 September^[3] or 19 October^[4] 1917 as USS Submarine Chaser No. 21, abbreviated at the time as USS S.C. 21.

Assigned to the Second Naval District, S.C. 21 operated with the Experimental Unit at New London, Connecticut.

When the U.S. Navy adopted its modern hull number system on 17 July 1920, Submarine Chaser No. 21 was classified as SC-21 and her name was shortened to USS SC-21.

On 24 June 1921, the Navy sold SC-21 to Joseph G. Hitner of Philadelphia, Pennsylvania.